The present invention relates to a surgical needle of eyeless type, a method of manufacturing the needle, and an apparatus for carrying out the method.
A surgical needle of eyeless type is known, in which a bore is formed in a proximal end of the needle and extends along an axis thereof. An end of a suture is inserted into the bore in the proximal end of the needle, and the proximal end of the needle is then staked, whereby the suture can be attached to the needle. Usually, there are known two methods of manufacturing the surgical needle having the proximal end formed therein with the bore.
First one of the two known methods is disclosed in Japanese patent application Laid-Open Nos. 52-111294, 60-170590 and 60-184485 Japanese Patent Publication No. 61-58172, Japanese Utility Model Publication No. 56-37918 and Japanese Utility Model application Laid-Open No. 55-43691, in which a drill or a beam energy is used to form the bore in the proximal end of the surgical needle. It is difficult for the first method, however, to form the small diameter bore correctly along the axis of the needle which is also small in diameter.
The second method is disclosed in Japanese Utility Model Publication No. 28-3184, in which a pipe member is welded to an end face of the proximal end of a needle member. In the second method, since a hollow portion of the pipe member can be used as a bore for attaching a suture, the bore-forming operation like the first method is dispensed with. Further, it is easy for the second method to manufacture a small diameter surgical needle having therein a small diameter bore extending along the axis of the surgical needle. The Japanese utility model does not specifically describe in what manner the pipe member is welded to the proximal end of the needle member. At that time, however, welding has practically been performed in the following manner. That is, the pipe member has been welded to the proximal end of the needle member by means of a so-called butt welding, in which an end face of the pipe member is butted under pressure against an end face of the proximal end of the needle member, and portions of the respective needle and pipe members adjacent the junction therebetween are welded to each other by heat generated due to electric resistance between both the end faces. It is necessary for the butt welding, however, to apply force to the pipe member and the needle member along an axis common to them during the welding operation such that the pipe member and the needle member are urged against each other. Because of such force, melted material tends to be forced out to form flash, so that a step of trimming is required after the welding operation. This trimming operation is troublesome because the surgical needle is very small in diameter, resulting in an increase of the manufacturing cost. Moreover, the melted metal flows under the urging force also into the hollow portion of the pipe member, so that variation occurs in the depths of the bores in the respective surgical needles, which bores are formed respectively by the hollow portions of the pipe members.
Additionally, as the relevant prior art, there is Japanese patent application Laid-Open No. 61-45745 corresponding to U.S. Ser. No. 632,343 filed on July 19, 1984, which discloses coloring of surgical needles. In this connection, there is also U.S. Ser. No. 905,521 filed on Sept. 10, 1986 in the name of the same assignee as this application.
Japanese Patent Publication No. 58-39544 and Japanese patent application Laid-Open Nos. 49-61980 and 50-119487 disclose a technique in which the suture is drawn out of the surgical needle in order to simplify and facilitate separation between the surgical needle and the suture after the suture has been pierced through a bodily tissue at the surgical operation. Japanese Utility Model application Laid-Open No. 61-109505 discloses a technique in which a part of the suture adjacent the surgical needle is weakened locally. Furthermore, Japanese Utility Model Application Laid-Open No. 61-109506 discloses a technique in which the suture is connected to the surgical needle by a special connector element.
Japanese Utility Model Publication No. 60-25219 discloses a technique for annealing the proximal end of the surgical needle formed of austenitic stainless steel.